Electric pump for a hybrid vehicle

ABSTRACT

A hydraulic system for a hybrid module which is located between an engine and a transmission includes a parallel arrangement of a mechanical pump and an electric pump. Each pump is constructed and arranged to deliver oil to other portions of the hydraulic system depending on the operational mode. Three operational modes are described including an electric mode, a transition mode, and a cruise mode. Various monitoring and control features are incorporated into the hydraulic system.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No. PCT/US2013/076472 filed Dec. 19, 2013, which claims the benefit of U.S. Provisional Application No. 61/781,458 filed Mar. 14, 2013, which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

With the growing concern over global climate change as well as oil supplies, there has been a recent trend to develop various hybrid systems for motor vehicles. While numerous hybrid systems have been proposed, the systems typically require significant modifications to the drive trains of the vehicles. These modifications make it difficult to retrofit the systems to existing vehicles. Moreover, some of these systems have a tendency to cause significant power loss, which in turn hurts the fuel economy for the vehicle. Thus, there is a need for improvement in this field.

One of the areas for improvement is in the construction and arrangement of the hydraulic system. Hybrid vehicles, and in particular the hybrid module associated with such a vehicle, have various lubrication and cooling needs which depend on engine conditions and operational modes. In order to address these needs, oil is delivered by at least one hydraulic pump. The operation of each hydraulic pump is controlled, based in part on the lubrication and cooling needs and based in part on the prioritizing when one or more hydraulic pump is included as part of the hydraulic system of the hybrid vehicle. The prioritizing between hydraulic pumps is based in part on the needs and based in part on the operational state or mode of the hybrid vehicle. In this regard, an electric (oil) pump can be used in combination with a mechanical (oil) pump.

SUMMARY

The hydraulic system (and method) described herein is part of a hybrid module used within a hybrid system adapted for use in vehicles and suitable for use in transportation systems and into other environments. The cooperating hybrid system is generally a self-contained and self-sufficient system which is able to function without the need to significantly drain resources from other systems in the corresponding vehicle or transportation system. The hybrid module includes an electric machine (eMachine).

This self-sufficient design in turn reduces the amount of modifications needed for other systems, such as the transmission and lubrication systems, because the capacities of the other systems do not need to be increased in order to compensate for the increased workload created by the hybrid system. For instance, the hybrid system incorporates its own lubrication and cooling systems that are able to operate independently of the transmission and the engine. The fluid circulation system, which can act as a lubricant, hydraulic fluid, and/or coolant, includes a mechanical pump for circulating a fluid, along with an electric pump that supplements workload for the mechanical pump when needed. As will be explained in further detail below, this dual mechanical/electric pump system helps to reduce the size and weight of the required mechanical pump, and if desired, also allows the system to run in a complete electric mode in which the electric pump solely circulates the fluid. The focus of this disclosure is directed at the electric pump.

More specifically, the described hydraulic system (for purposes of the exemplary embodiment) is used in conjunction with a hybrid electric vehicle (HEV). Included as part of the described hydraulic system is a parallel arrangement of a mechanical oil pump and an electric oil pump. The control of each pump and the sequence of operation of each pump depends in part on the operational state or the mode of the hybrid vehicle. Various system modes are described herein relating to the hybrid vehicle. As for the hydraulic system disclosed herein, there are three modes which are specifically described and these three modes include an electric mode (eMode), a transition mode, and a cruise mode.

As will be appreciated from the description which follows, the described hydraulic system (and method) is constructed and arranged for addressing the need for component lubrication and for cooling those portions of the hybrid module which experience an elevated temperature during operation of the vehicle. The specific construction and operational characteristics provide an improved hydraulic system for a hydraulic module.

The compact design of the hybrid module has placed demands and constraints on a number of its subcomponents, such as its hydraulics and the clutch. To provide an axially compact arrangement, the piston for the clutch has a recess in order to receive a piston spring that returns the piston to a normally disengaged position. The recess for the spring in the piston creates an imbalance in the opposing surface areas of the piston. This imbalance is exacerbated by the high centrifugal forces that cause pooling of the fluid, which acts as the hydraulic fluid for the piston. As a result, a nonlinear relationship for piston pressure is formed that makes accurate piston control extremely difficult. To address this issue, the piston has an offset section so that both sides of the piston have the same area and diameter. With the areas being the same, the operation of the clutch can be tightly and reliably controlled. The hydraulics for the clutch also incorporate a spill over feature that reduces the risk of hydrostatic lock, while at the same time ensures proper filling and lubrication.

In addition to acting as the hydraulic fluid for the clutch, the hydraulic fluid also acts as a coolant for the eMachine as well as other components. The hybrid module includes a sleeve that defines a fluid channel that encircles the eMachine for cooling purposes. The sleeve has a number of spray channels that spray the fluid from the fluid channel onto the windings of the stator, thereby cooling the windings, which tend to generally generate the majority of the heat for the eMachine. The fluid has a tendency to leak from the hybrid module and around the torque converter. To prevent power loss of the torque converter, the area around the torque converter should be relatively dry, that is, free from the fluid. To keep the fluid from escaping and invading the torque converter, the hybrid module includes a dam and slinger arrangement. Specifically, the hybrid module has a impeller blade that propels the fluid back into the eMachine through a window or opening in a dam member. Subsequently, the fluid is then drained into the sump so that it can be scavenged and recirculated.

The hybrid module has a number of different operational modes. During the start mode, the battery supplies power to the eMachine as well as to the electric pump. Once the electric pump achieves the desired oil pressure, the clutch piston is stroked to apply the clutch. With the clutch engaged, the eMachine applies power to start the engine. During the electro-propulsion only mode the clutch is disengaged, and only the eMachine is used to power the torque converter. In the propulsion assist mode, the engine's clutch is engaged, and the eMachine acts as a motor in which both the engine and eMachine drive the torque converter. While in a propulsion-charge mode, the clutch is engaged, and the internal combustion engine solely drives the vehicle. The eMachine is operated in a generator mode to generate electricity that is stored in the energy storage system. The hybrid module can also be used to utilize regenerative braking (i.e., regenerative charging). During regenerative braking, the engine's clutch is disengaged, and the eMachine operates as a generator to supply electricity to the energy storage system. The system is also designed for engine compression braking, in which case the engine's clutch is engaged, and the eMachine operates as a generator as well.

In addition, the system is also designed to utilize both power takeoff (PTO) and electronic PTO (ePTO) modes in order to operate ancillary equipment such as cranes, refrigeration systems, hydraulic lifts, and the like. In a normal PTO mode, the clutch and the PTO system are engaged, and the internal combustion engine is then used to power the ancillary equipment. In an ePTO state, the clutch is disengaged and the eMachine acts as a motor to power the ancillary equipment via the PTO. While in the PTO or ePTO operational modes, the transmission can be in neutral or in gear, depending on the requirements.

Further forms, objects, features, aspects, benefits, advantages, and embodiments of the present invention will become apparent from a detailed description and drawings provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagrammatic view of one example of a hybrid system.

FIG. 2 illustrates a diagrammatic view of one hydraulic system suitable for use in the FIG. 1 hybrid system.

FIG. 3 is a perspective view of a hybrid module coupled to a transmission that is used in the FIG. 1 hybrid system.

FIG. 4 is a top view of the FIG. 4 hybrid module-transmission subassembly.

FIG. 5 is a perspective, partial cross-sectional view of the hybrid module-transmission subassembly illustrated in FIG. 3.

FIG. 6 illustrates a diagrammatic view of the FIG. 2 hydraulic system when the hydraulic system is in an eMode.

FIG. 7 illustrates a diagrammatic view of the FIG. 2 hydraulic system when the hydraulic system is in a Transition Mode.

FIG. 8 illustrates a diagrammatic view of the FIG. 2 hydraulic system when the hydraulic system is in a Cruise Mode.

FIG. 9 is a perspective view of an electric pump according to one embodiment of the present disclosure.

FIG. 10 is an electrical schematic associated with the FIG. 9 electric pump according to the present disclosure.

FIG. 11 is an exploded perspective view of an electric pump according to another embodiment of the present disclosure.

FIG. 12 is a perspective view of the FIG. 11 electric pump as assembled.

FIG. 12A is a partial perspective view of an alternative embodiment with a three-bolt mounting pattern.

FIG. 13 is a partial perspective view of the FIG. 12 electric pump, as viewed from a different direction.

FIG. 14 is a partial perspective view of the FIG. 12 electric pump, in full section.

FIG. 15 is a partial perspective view of the FIG. 12 electric pump, in full section.

FIG. 16 is a partial perspective view of the FIG. 12 electric pump, in full section.

FIG. 17 is partial perspective view of the FIG. 12 electric pump, showing an O-ring location.

FIG. 18 is a partial perspective view of the FIG. 12 electric pump, showing a new dowel pin location.

FIG. 19 is a partial perspective view of the FIG. 12A electric pump, showing an alternate connector orientation.

FIG. 20 is a partial perspective view of the FIG. 12 electric pump, showing a shortened inlet/outlet conduit length.

FIG. 21 is a partial perspective view of one bolt location of the FIG. 12 electric pump, showing increased clearance around the bolt head.

FIG. 22 is a diagrammatic illustration of phase 1 of the assembly sequence of installing the FIG. 12 electric pump into a hybrid module.

FIG. 23 is a diagrammatic illustration of phase 2 of the assembly sequence.

FIG. 24 is a diagrammatic illustration of phase 3 of the assembly sequence.

FIG. 25 is a diagrammatic illustration of phase 4 of the assembly sequence.

FIG. 26 is a perspective view of a dowel pin showing a vent groove.

FIG. 27 is a perspective view of the use of tamper-proof threaded fasteners.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated device and its use, and such further applications of the principles of the disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates.

FIG. 1 shows a diagrammatic view of a hybrid system 100 according to one embodiment. The hybrid system 100 illustrated in FIG. 1 is adapted for use in commercial-grade trucks as well as other types of vehicles or transportation systems, but it is envisioned that various aspects of the hybrid system 100 can be incorporated into other environments. As shown, the hybrid system 100 includes an engine 102, a hybrid module 104, an automatic transmission 106, and a drive train 108 for transferring power from the transmission 106 to wheels 110. The hybrid module 104 incorporates an electrical machine, commonly referred to as an eMachine 112, and a clutch 114 that operatively connects and disconnects the engine 102 with the eMachine 112 and the transmission 106.

The hybrid module 104 is designed to operate as a self-sufficient unit, that is, it is generally able to operate independently of the engine 102 and transmission 106. In particular, its hydraulics, cooling and lubrication do not directly rely upon the engine 102 and the transmission 106. The hybrid module 104 includes a sump 116 that stores and supplies fluids, such as oil, lubricants, or other fluids, to the hybrid module 104 for hydraulics, lubrication, and cooling purposes. While the terms oil or lubricant or lube will be used interchangeably herein, these terms are used in a broader sense to include various types of lubricants, such as natural or synthetic oils, as well as lubricants having different properties. To circulate the fluid, the hybrid module 104 includes a mechanical pump 118 and an electric pump 120 in cooperation with a hydraulic system 200 (see FIG. 2). With this parallel combination of both the mechanical pump 118 and electric pump 120, there are opportunities to reduce the overall size and perhaps the total cost for the pumps. The electric pump 120 cooperates with the mechanical pump 118 to provide extra pumping capacity when required. The electric pump 120 is also used for hybrid system needs when there is no drive input to operate the mechanical pump 118. In addition, it is contemplated that the flow through the electric pump 120 can be used to detect low fluid conditions for the hybrid module 104.

The hybrid system 100 further includes a cooling system 122 that is used to cool the fluid supplied to the hybrid module 104 as well as the water-ethylene-glycol (WEG) to various other components of the hybrid system 100. In one variation, the WEG can also be circulated through an outer jacket of the eMachine 112 in order to cool the eMachine 112. Although the hybrid system 100 has been described with respect to a WEG coolant, other types of antifreezes and cooling fluids, such as water, alcohol solutions, etc., can be used. With continued reference to FIG. 1, the cooling system 122 includes a fluid radiator 124 that cools the fluid for the hybrid module 104. The cooling system 122 further includes a main radiator 126 that is configured to cool the antifreeze for various other components in the hybrid system 100. Usually, the main radiator 126 is the engine radiator in most vehicles, but the main radiator 126 does not need to be the engine radiator. A cooling fan 128 flows air through both fluid radiator 124 and main radiator 126. A circulating or coolant pump 130 circulates the antifreeze to the main radiator 126. It should be recognized that other various components besides the ones illustrated can be cooled using the cooling system 122. For instance, the transmission 106 and/or the engine 102 can be cooled as well via the cooling system 122.

The eMachine 112 in the hybrid module 104, depending on the operational mode, at times acts as a generator and at other times as a motor. When acting as a motor, the eMachine 112 draws alternating current (AC). When acting as a generator, the eMachine 112 creates AC. An inverter 132 converts the AC from the eMachine 112 and supplies it to an energy storage system 134. In the illustrated example, the energy storage system 134 stores the energy and resupplies it as direct current (DC). When the eMachine 112 in the hybrid module 104 acts as a motor, the inverter 132 converts the DC power to AC, which in turn is supplied to the eMachine 112. The energy storage system 134 in the illustrated example includes three energy storage modules 136 that are daisy-chained together to supply high voltage power to the inverter 132. The energy storage modules 136 are, in essence, electrochemical batteries for storing the energy generated by the eMachine 112 and rapidly supplying the energy back to the eMachine 112. The energy storage modules 136, the inverter 132, and the eMachine 112 are operatively coupled together through high voltage wiring as is depicted by the line illustrated in FIG. 1. While the illustrated example shows the energy storage system 134 including three energy storage modules 136, it should be recognized that the energy storage system 134 can include more or less energy storage modules 136 than is shown. Moreover, it is envisioned that the energy storage system 134 can include any system for storing potential energy, such as through chemical means, pneumatic accumulators, hydraulic accumulators, springs, thermal storage systems, flywheels, gravitational devices, and capacitors, to name just a few examples.

High voltage wiring connects the energy storage system 134 to a high voltage tap 138. The high voltage tap 138 supplies high voltage to various components attached to the vehicle. A DC-DC converter system 140, which includes one or more DC-DC converter modules 142, converts the high voltage power supplied by the energy storage system 134 to a lower voltage, which in turn is supplied to various systems and accessories 144 that require lower voltages. As illustrated in FIG. 1, low voltage wiring connects the DC-DC converter modules 142 to the low voltage systems and accessories 144.

The hybrid system 100 incorporates a number of control systems for controlling the operations of the various components. For example, the engine 102 has an engine control module (ECM) 146 that controls various operational characteristics of the engine 102 such as fuel injection and the like. A transmission/hybrid control module (TCM/HCM) 148 substitutes for a traditional transmission control module and is designed to control both the operation of the transmission 106 as well as the hybrid module 104. The transmission/hybrid control module 148 and the engine control module 146 along with the inverter 132, energy storage system 134, and DC-DC converter system 140 communicate along a communication link as is depicted in FIG. 1.

To control and monitor the operation of the hybrid system 100, the hybrid system 100 includes an interface 150. The interface 150 includes a shift selector 152 for selecting whether the vehicle is in drive, neutral, reverse, etc., and an instrument panel 154 that includes various indicators 156 of the operational status of the hybrid system 100, such as check transmission, brake pressure, and air pressure indicators, to name just a few.

As noted before, the hybrid system 100 is configured to be readily retrofitted to existing vehicle designs with minimal impact to the overall design. All of the systems including, but not limited to, mechanical, electrical, cooling, controls, and hydraulic systems, of the hybrid system 100 have been configured to be a generally self-contained unit such that the remaining components of the vehicle do not need significant modifications. The more components that need to be modified, the more vehicle design effort and testing is required, which in turn reduces the chance of vehicle manufacturers adopting newer hybrid designs over less efficient, preexisting vehicle designs. In other words, significant modifications to the layout of a preexisting vehicle design for a hybrid retrofit require, then, vehicle and product line modifications and expensive testing to ensure the proper operation and safety of the vehicle, and this expense tends to lessen or slow the adoption of hybrid systems. As will be recognized, the hybrid system 100 not only incorporates a mechanical architecture that minimally impacts the mechanical systems of pre-existing vehicle designs, but the hybrid system 100 also incorporates a control/electrical architecture that minimally impacts the control and electrical systems of pre-existing vehicle designs.

Further details regarding the hybrid system 100 and its various subsystems, controls, components and modes of operation are described in Provisional Patent Application No. 61/381,615, filed Sep. 10, 2010, which is hereby incorporated by reference in its entirety.

Referring to FIG. 2, there is illustrated in diagrammatic form a hydraulic system 200 which is suitably constructed and arranged for use with hybrid system 100. More particularly, hydraulic system 200 is a portion of hybrid module 104. Since the FIG. 2 illustration includes components which interface with a sump module assembly 202, broken lines 204 are used in FIG. 2 to denote, in diagrammatic form, the functional locations of the oil connections from other hydraulic components to the sump module assembly 202. Lower case letters are used in conjunction with reference numeral 204 in order to distinguish the various broken line locations (204 a, 204 b, etc.). For example, the sump 116 is part of the sump module assembly 202, while mechanical pump 118 and electric pump 120 are not technically considered to be actual component parts of the sump module assembly 202, though this convention is somewhat arbitrary. The mechanical pump 118 and the electric pump 120 each have an oil connection with the sump module assembly 202. Sump 116 is independent of the sump for the automatic transmission 106. Broken line 204 a diagrammatically illustrates the location of flow communication between the mechanical pump inlet conduit 206 and sump 116. Similarly, broken line 204 b denotes the location of flow communication between the electric pump inlet conduit 208 and sump 116. Inlet conduit 206 defines inlet conduit opening 206 a. Inlet conduit 208 defines inlet conduit opening 208 a.

On the flow exiting sides of the two oil pumps, broken line 204 c denotes the location where the outlet 210 of mechanical pump 118 is in flow connection (and flow communication with the sump module assembly 202. Broken line 204 d denotes the location where the outlet 212 of the electric pump 120 is in flow connection (and flow communication) with the sump module assembly 202. This broken line convention is used throughout the FIG. 2 illustration. However, this convention is simply for convenience in explaining the exemplary embodiment and is not intended to be structurally limiting in any manner. While the other components which have flow connections to the sump module assembly 202 are not technically considered part of the sump module assembly, these other components, such as the mechanical pump 118 and the electric pump 120, are considered part of the overall hydraulic system 200.

With continued referenced to FIG. 2, hydraulic system 200 includes a main regulator valve 218, main regulator by-pass valve 220, control main valve 222, exhaust back fill valve 224, cooler 226, filter 228, lube splitter valve 230, clutch trim valve 232, accumulator 234, solenoid 236, and solenoid 238. It will be appreciated that these identified component parts and subassemblies of hydraulic system 200 are connected with various flow conduits and that pop off valves are strategically positioned to safeguard against excessive pressure levels. Further, downstream from the lube splitter valve 230 are illustrated elements which are intended to receive oil. The first priority of the available oil at the lube splitter valve 230 is for lubrication and cooling of bearings 244 and gears or other accessories which are in need of cooling and lubrication. The second priority, once the first priority has been satisfied, is to deliver oil to motor sleeve 246.

The mechanical pump 118 is constructed and arranged to deliver oil to the main regulator valve 218 via conduit 250. One-way valve 248 is constructed and arranged for flow communication with conduit 250 and is positioned downstream from the mechanical pump 118. Valve 248 is constructed and arranged to prevent backwards flow when the engine and (accordingly) the mechanical pump are OFF. Valve 248 includes a ball and spring arrangement set at a threshold of 5 psi. Branch conduits 252 and 254 provide flow connections to the main regulator valve 218 and the main regulator by-pass valve 220, respectively. The electric pump 120 is constructed and arranged to deliver oil to the main regulator by-pass valve 220 via conduit 256. The main regulator by-pass valve 220 is in flow communication with main regulator valve 218 via conduit 258, with control main valve 222 via conduit 260, with clutch trim valve 232 via conduit 262, with cooler 226 via conduit 264 and with solenoid 238 via conduit 266.

The main regulator valve 218 is in flow communication with conduit 264 via conduit 272. Conduit 274 is in flow communication with the main regulator valve 218 and connects to conduit 276 which extends between control main valve 222 and solenoid 236. Branch conduit 278 establishes a flow path between conduit 274 and solenoid 238. Conduit 280 establishes flow communication between main regulator valve 218 and clutch trim valve 232. Conduit 282 establishes flow communication between control main valve 222 and exhaust back fill valve 224. Conduit 284 establishes flow communication between exhaust back fill valve 224 and clutch trim valve 232. Conduit 286 establishes flow communication between clutch trim valve 232 and accumulator 234. Conduit 288 establishes flow communication between clutch trim valve 232 and conduit 276. Conduit 290 establishes flow communication between solenoid 236 and clutch trim valve 232. Conduit 292 establishes a flow path (main) between conduit 280 and control main valve 222. Conduit 294 establishes a control branch flow connection between conduit 276 and control main valve 222. Other flow connections and conduits are illustrated in FIG. 2 and the corresponding flow path is readily apparent.

Considering the diagrammatic form of FIG. 2, it will be appreciated that the various flow connections and flow conduits may assume any one of a variety of forms and constructions so long as the desired oil flow can be achieved with the desired flow rate and the desired flow timing and sequence. The hydraulic system 200 description makes clear what type of oil flow is required between what components and subassemblies and the operational reason for each flow path. The hydraulic system 200 description which corresponds to what is illustrated in FIG. 2 is directed to what components and subassemblies are in oil flow communication with each other, depending on the hybrid system 100 conditions and the operational mode.

Before describing each of the three modes of operation applicable to hydraulic system 200, the relationship between and some of the construction details regarding the mechanical pump 118 and the electric pump 120 will be described. Understanding a few of the pump basics should facilitate a better understanding of the three modes of operation selected for further discussion regarding the overall hydraulic system.

Turning now to some of the mechanical structures, FIG. 3 illustrates a perspective view of the hybrid module 104 attached to the automatic transmission 106 to form a hybrid module-transmission subassembly 300, and FIG. 4 shows a top view of the subassembly 300. As can be seen in FIG. 3, the hybrid module 104 includes a hybrid module housing 302 that has an engine engagement side 304 where the hybrid module 104 engages the engine 102 and a transmission engagement side 306 where the hybrid module 104 engages the automatic transmission 106. The hybrid module 104 further includes a high voltage connector box 308 in which high voltage wires 310 from the inverter 132 are received. The three-phase alternating current is transmitted via the high voltage wires 310 to the high voltage connector box 308.

The hybrid module 104 is constructed so as to fit between the engine 102 and the automatic transmission 106 without any significant modification to the overall vehicular design. In essence, the drive shaft of the vehicle is simply shortened, and the hybrid module 104 is inserted between the engine 102 and the automatic transmission 106, thereby filling the space in between which the longer driveshaft once occupied. With that said, the hybrid module 104 is designed specifically to have a compact design so as to be easily retrofitted into existing vehicle designs. Moreover, the hybrid module 104 as well as the rest of the components are designed to be easily assembled and retrofitted to a preexisting automatic transmission 106. As noted before, the hybrid module 104 is also designed to be a self-contained/self-sufficient unit in which it is able to function without draining resources from other systems in the vehicle. For instance, the lubrication and cooling system for the hybrid module 104 generally operates independent of the engine 102 and the automatic transmission 106. As such, it gives the hybrid module 104 greater flexibility in its various operational modes. This self-sufficient design in turn reduces the amount of modifications needed for other systems, such as the transmission 106, because the capacities of the other systems do not need to be increased in order to compensate for any increased workload created by the hybrid module 104. As one example, looking at FIG. 3, the hybrid module 104 has the sump 116 that is independent of the sump for the automatic transmission 106. The electric pump 120 supplements the mechanical pump 118, which will be described later with respect to FIG. 5, in order to pump fluid through the hybrid module 104.

FIG. 5 shows a front, perspective view that includes a partial cross section through the hybrid module 104 from the perspective of the engine engagement side 304 of the hybrid module 104. On the engine engagement side 304, the hybrid module 104 has the mechanical pump 118 with a pump housing 402 that is secured to the hybrid module housing 302. A pump drive gear 404 which is secured to an input shaft 406 is used to drive the mechanical pump 118. The drive gear 404 in one example is secured to the input shaft 406 via a snap ring and key arrangement, but it is contemplated that the drive gear 404 can be secured in other manners. The mechanical pump 118 in conjunction with the electric pump 120 supplies fluid for lubrication, hydraulics, and/or cooling purposes to the hybrid module 104. By incorporating the electric pump 120 in conjunction with the mechanical pump 118, the mechanical pump 118 can be sized smaller, which in turn reduces the required space it occupies as well as reduces the cost associated with the mechanical pump 118. Moreover, the electric pump 120 facilitates lubrication even when the engine 102 is off. This in turn facilitates electric-only operating modes as well as other modes of the hybrid system 100. Both the mechanical pump 118 and the electric pump 120 recirculate fluid from the sump 116. The fluid is then supplied to the remainder of the hybrid module 104 via holes, ports, openings and other passageways traditionally found in transmissions for circulating oil and other fluids. A clutch supply port 408 supplies oil that hydraulically applies or actuates the clutch 114. In the illustrated embodiment, the clutch supply port 408 is in the form of a tube, but is envisioned it can take other forms, such as integral passageways within the hybrid module 104, in other examples.

As mentioned before, the hybrid module 104 is designed to be easily assembled to both the engine 102 and the automatic transmission 106. To facilitate a relatively easy connection to the engine 102, the input shaft 406 at the engine engagement side 304 has a series of splines 410 that are adapted to engage an input drive disc of the engine 102. The splines 410 reduce the need for reorienting the crankshaft of the engine 102 in order to secure the hybrid module 104 to the engine 102 in the manner of a conventional bolt joint flex plate drive system. The input shaft 406 is also configured to be able to be slid out of the hybrid module 104 for facilitating servicing of the input shaft 406 as well as components associated with the input shaft 406. To further secure the hybrid module 104 to the engine 102, the hybrid module housing 302 has an engine flange 412 with bolt openings 414 in which bolts 416 are used to secure the hybrid module 104 to the engine 102.

The operation of the hybrid system 100 involves or includes various operational modes or status conditions, also referred to herein as “system modes” or simply “modes”. The principal hybrid system 100 modes are summarized in Table 1 which is provided below:

TABLE I SYSTEM MODES Mode Clutch Motor PTO Transmission Engine Start Engaged Motor Inoperative Neutral Charge Neutral Engaged Generator Inoperative Neutral eAssist Engaged Motor Inoperative In Gear Propulsion eDrive Disengaged Motor Inoperative In Gear Propulsion Engaged Generator Inoperative In Gear with Charge Regeneration Disengaged Generator Inoperative In Gear Charging No Charge Engaged N/A Inoperative In Gear Braking PTO Engaged N/A Operative Neutral ePTO Disengaged Motor Operative Neutral

During an initialization and/or startup mode, the electric pump 120 is activated by the transmission/hybrid control module 148 so as to circulate fluid through the hybrid module 104. The electric pump 120 receives its power from the energy storage system 134 via the inverter 132 (FIG. 1). Once sufficient oil pressure is achieved, the clutch 114 is engaged. At the same time or before, the PTO is inoperative or remains inoperative, and the transmission 106 is in neutral or remains in neutral. With the clutch 114 engaged, the eMachine 112 acts as a motor and in turn cranks the engine 102 in order to start (i.e., spin/crank) the engine. When acting like a motor, the eMachine 112 draws power from the energy storage system 134 via the inverter 132. Upon the engine 102 starting, the hybrid system 100 shifts to a charge neutral mode in which the fuel is on to the engine 102, the clutch 114 is engaged, and the eMachine 112 switches to a generator mode in which electricity generated by its rotation is used to charge the energy storage modules 136. While in the charge neutral mode, the transmission remains in neutral.

From the charge neutral mode, the hybrid system 100 can change to a number of different operational modes. The various PTO operational modes can also be entered from the charge neutral mode. As should be understood, the hybrid system is able to move back and forth between the various operational modes. In the charge neutral mode, the transmission is disengaged, that is, the transmission is in neutral. Referring to Table 1, the hybrid system 100 enters a propulsion assist or eAssist propulsion mode by placing the transmission 106 in gear and having the eMachine 112 act as a motor.

During the eAssist propulsion mode, a PTO module is inoperative and the fuel to the engine 102 is on. In the eAssist propulsion mode, both the engine 102 and the eMachine 112 work in conjunction to power the vehicle. In other words, the energy to power the vehicle comes from both the energy storage system 134 as well as the engine 102. While in the eAssist propulsion mode, the hybrid system 100 can then transition back to the charge neutral mode by placing the transmission 106 back into neutral and switching the eMachine 112 to a generator mode.

From the eAssist propulsion mode, the hybrid system 100 can transition to a number of different operational states. For instance, the hybrid system 100 can transition from the eAssist propulsion mode to an electrical or eDrive mode in which the vehicle is solely driven by the eMachine 112. In the eDrive mode, the clutch 114 is disengaged, and the fuel to the engine 102 is turned off so that the engine 102 is stopped. The transmission 106 is placed in a driving gear. As the eMachine 112 powers the transmission 106, the PTO module is inoperative. While in the eDrive mode, the electric pump 120 solely provides the hydraulic pressure for lubricating the hybrid module 104 and controlling the clutch 114, because the mechanical pump 118 is not powered by the stopped engine 102. During the eDrive mode, the eMachine 112 acts as a motor. To return to the eAssist propulsion mode, the electric pump 120 remains on to provide the requisite back pressure to engage the clutch 114. Once the clutch 114 is engaged, the engine 102 is spun and fuel is turned on to power the engine 102. When returning to the eAssist propulsion mode from the eDrive mode, both the eMachine 112 and the engine 102 drive the transmission 106, which is in gear.

The hybrid system 100 also has a propulsion charge mode, a regenerative braking charge mode, and a compression or engine-braking mode. The hybrid system 100 can transition to the propulsion charge mode from the charge neutral mode, the eAssist propulsion mode, the regenerative braking charge mode, or the engine-braking mode. When in the propulsion charge mode, the engine 102 propels the vehicle while the eMachine 112 acts as a generator. During the propulsion charge mode, the clutch 114 is engaged such that power from the engine 102 drives the eMachine 112 and the transmission 106, which is in gear. Again, during the propulsion charge mode, the eMachine 112 acts as a generator, and the inverter 132 converts the alternating current produced by the eMachine 112 to direct current, which is then stored in the energy storage system 134. In this mode, the PTO module is in an inoperative state. While in the propulsion charge mode, the mechanical pump 118 generally handles most of the oil pressure and lubricant needs, while the electric pump 120 provides eMachine cooling. The load between the mechanical 118 and electric 120 pumps is balanced to minimize power loss.

The hybrid system 100 can transition to a number of operational modes from the propulsion charge mode. For example, the hybrid system 100 can transition to the charge neutral mode from the propulsion charge mode by placing the transmission 106 in neutral. The hybrid system 100 can return to the propulsion charge mode by placing the transmission 106 into gear. From the propulsion charge mode, the hybrid system 100 can also switch to the propulsion assist mode by having the eMachine 112 act as an electric motor in which electricity is drawn from the energy storage system 134 to the eMachine 112 such that the eMachine 112 along with the engine 102 drive the transmission 106. The regenerative charge mode can be used to recapture some of the energy that is normally lost during braking. The hybrid system 100 can transition from the propulsion charge mode to the regenerative charge mode by simply disengaging the clutch 114. In some instances, it may be desirable to use the engine-braking mode to further slow down the vehicle and/or to reduce wear of the brakes. Transitioning to the engine-braking mode can be accomplished from the propulsion charge mode by turning off the fuel to the engine 102. During the engine-braking mode, the eMachine 112 acts as a generator. The hybrid system 100 can return to the propulsion charge mode by turning back on the fuel to the engine 102. Simply disengaging the clutch 114 will then switch the hybrid system 100 to the regenerative charging mode.

The hybrid system 100 is able to conserve energy normally lost during braking by utilizing the regenerative braking/charge mode. During the regenerative charge mode, the clutch 114 is disengaged. The eMachine 112 acts as a generator while the transmission 106 is in gear. The power from the wheels of the vehicle is transferred through the transmission 106 to the eMachine 112, which acts as a generator to reclaim some of the braking energy and in turn helps to slow down the vehicle. The recovered energy via the inverter 132 is stored in the energy storage system 134. As noted in Table 1 above, during this mode the PTO module is inoperative.

The hybrid system 100 can transition from the regenerative charge mode to any number of different operational modes. For instance, the hybrid system 100 can return to the propulsion assist mode by engaging the clutch 114 and switching the eMachine 112 to act as a motor. From the regenerative charge mode, the hybrid system 100 can also return to the propulsion charge mode by engaging the clutch 114, and switching the eMachine 112 to the generator role. The hybrid system 100 can also switch to the engine-braking mode from the regenerative charge mode by turning off the fuel to the engine 102 and engaging the clutch.

In addition to the regenerative braking mode, the hybrid system 100 can also utilize the engine-braking mode in which compression braking of the engine 102 is used to slow down the vehicle. During the engine braking mode, the transmission 106 is in gear, the PTO module is inoperative, and the eMachine 112 is acting as a generator so as to recover some of the braking energy, if so desired. However, during other variations of the engine-braking mode, the eMachine 112 does not need to act as a generator such that the eMachine 112 draws no power for the energy store system module 134. To transmit the energy from the vehicle's wheels, the engine clutch 114 is engaged and the power is then transmitted to the engine 102 while the fuel is off. In another alternative, a dual regenerative and engine braking mode can be used in which both the engine 102 and the eMachine 112 are used for braking and some of the braking energy from the eMachine 112 is recovered by the energy storage system module 134.

The hybrid system 100 can transition from the engine-braking mode to any number of different operational modes. As an example, the hybrid system 100 can switch from the engine-braking mode to the propulsion assist mode by turning on the fuel to the engine 102 and switching the eMachine 112 to act as an electric motor. From the engine-braking mode, the hybrid system 100 can also switch to the propulsion charge mode by turning back on the fuel to the engine 102. In addition, the hybrid system 100 can switch from the engine-braking mode to the regenerative charge mode by turning on the fuel to the engine 102 and disengaging the clutch 114.

When the PTO is used, the vehicle can be stationary or can be moving (e.g., for refrigeration systems). From the charge neutral mode, the hybrid system 100 enters a PTO mode by engaging the PTO. While in the PTO mode, the clutch 114 is engaged such that power from the engine 102 is transmitted to the now-operative PTO. During this PTO mode, the eMachine 112 acts as a generator drawing supplemental power from the engine 102 and transferring it via the inverter 132 to the energy storage system module 134. At the same time, the transmission 106 is in neutral so that the vehicle can remain relatively stationary, if desired. With the PTO operative, the ancillary equipment, such as the lift buckets, etc., can be used. The hybrid system 100 can return to the charge neutral mode by making the PTO inoperative.

During the PTO mode, the engine 102 is constantly running which tends to waste fuel as well as create unnecessary emissions in some work scenarios. Fuel can be conserved and emissions reduced from the hybrid system 100 by switching to an electric or ePTO mode of operation. When transitioning to the ePTO mode, the clutch 114, which transmits power from the engine 102, is disengaged and the engine 102 is stopped. During the ePTO mode, the eMachine 112 is switched to act as an electric motor and the PTO is operative. At the same time, the transmission 106 is in neutral and the engine 102 is stopped. Having the engine 102 turned off reduces the amount of emissions as well as conserves fuel. The hybrid system 100 can return from the ePTO mode to the PTO mode by continued operation of the electric pump 120, engaging the clutch 114 and starting the engine 102 with the eMachine 112 acting as a starter. Once the engine 102 is started, the eMachine 112 is switched over to act as a generator and the PTO is able to operate with power from the engine 102.

With the operation or system modes of hybrid system 100 (see Table 1) in mind, the hydraulic system 200 is now further described in the context of three modes of operation. These three modes include an Electric Mode (eMode), a Transition Mode, and a Cruise Mode. From the perspective of the status and conditions of hydraulic system mode the eMode conditions are diagrammatically illustrated in FIG. 6. The Transition Mode conditions are diagrammatically illustrated in FIG. 7. The Cruise Mode conditions are diagrammatically illustrated in FIG. 8.

Referring first to FIG. 6, in the eMode condition, as represented by hydraulic system 200 a, the engine and clutch are each in an “OFF” condition, and each solenoid 236 and 238 is an “OFF” condition. The electric pump 120 provides one hundred percent (100%) of the oil flow to the main regulator valve 218. With solenoid 238 in an “OFF” condition, there is no solenoid signal to the main regulator by-pass valve 220 and this component is also considered as being in an “OFF” condition. The main pressure is “knocked down” to 90 psi due to using only the electric pump 120 and considering its performance limitations. Any lube/cooling flow to the cooler 226 is the result of main regulator valve 218 overage.

Referring now to FIG. 7, in the Transition Mode condition as represented by hydraulic system 200 b, the engine may be in either an “ON” or “OFF” condition, the clutch is in an “ON” condition, solenoid 238 is “OFF”, and solenoid 236 is “ON”. The electric pump 120 and the mechanical pump 118 can supply a flow of oil to the main regular valve 218. The main pressure is knocked down to 90 psi and any lube/cooling flow to the cooler 226 is the result of main regulator valve 218 overage.

Referring now to FIG. 8, in the Cruise Mode, as represented by hydraulic system 200 c, the engine and clutch are each in an “ON” condition, and each solenoid 236 and 238 is an “ON” condition. In this condition, the mechanical pump 118 provides one hundred percent (100%) of the oil flow to the main regulator valve 218 and to the clutch control hydraulics. The electric pump 120 provides supplemental cooler flow (or what may be referred to as cooler flow “boost”). The main pressure is at the “normal” (i.e., not knocked down) level of 205 psi. The flow to the cooler 226 is by way of the main regulator valve 218 overage and supplemented by flow from the electric pump 120.

The three modes which have been described and illustrated in FIGS. 6-8 have been identified in conjunction with hydraulic systems 200 a, 200 b, and 200 c, respectively. This numbering scheme of letter suffixes is representative of the fact that the hardware, components, subassemblies, and conduits of hydraulic system 200 do not change with the different modes of operation. However, the operational status, the various ON/OFF conditions, etc. of the hardware, components, and subassemblies may change, depending on the particular item and the specific mode of operation.

While the three described modes for the hydraulic system 200 are based in part on the status or conditions of the engine, these modes are also based in part on the ON/OFF status of the referenced hardware, components, and subassemblies, including the mechanical pump 118 and the electric pump 120. The mechanical pump 118 is directly connected to the engine 102 such that when the engine is ON, the mechanical pump 118 is ON. When the engine 102 is OFF, the mechanical pump 118 is OFF. When ON, the mechanical pump 118 delivers oil to the entire hydraulic system. Any overage from the main regulator valve 218 is delivered to the cooler 226.

The ON/OFF status of the electric pump 120 and the speed of the electric pump 120 are controlled by the electronics of the hybrid module 104. The electric pump 120 delivers oil either to the hydraulic system 200 and/or to the cooler 226. When the mechanical pump 118 is either OFF or when its delivery of oil is insufficient, the electric pump 120 delivers oil to the hydraulic system. When the delivery of oil from the mechanical pump is sufficient, the electric pump 120 is able to be used for delivery of oil to the cooler for lube and motor cooling.

Reference has been made to the knocked down lower pressure level for certain operational modes. This knocked down pressure is associated with operation of the electric pump 120. Considering the various pressure levels and flow rates, the main pressure of the mechanical pump 118 is 205 psi. The main pressure of the electric pump 120 is 90 psi. For lube and cooling, the first 5.0 lpm of flow at approximately 30 psi is used for lube. Any excess flow up to approximately 15.0 lpm is delivered to the motor cooling sleeve 246. A maximum of 50 psi for the lube/cooling function is attained only after the motor cooling sleeve 240 is filled with oil. The clutch applied pressure is 205 psi nominal (1410 kPa) and 188 psi minimum (1300 kPa).

Referring now to FIG. 9, additional details of one embodiment of a suitable electric pump 120 are illustrated and described. The pump mechanism 500 includes a pump inlet 502 and a pump outlet 504. Ignoring for now the precise form of the mechanical connections between the pump inlet 502 and the sump 116, whether by inlet conduit 208 or by some other similar structure, inlet 502 has a generally cylindrical form and surrounds pump outlet 504. Pump outlet 504 is generally cylindrical and generally concentric with pump inlet 502. The outer surface 502 a of pump inlet 502 defines an annular recessed channel 502 b for receipt of O-ring 506. Similarly, the outer surface 504 a of pump outlet 504 defines an annular recessed channel 504 b for receipt of O-ring 508.

The electric motor and controller subassembly 514 includes an electrical connector 516 and an annular mounting flange 518. The mounting flange 518, illustrated with a bolt circle of externally-threaded mounting studs 520, could be alternatively constructed and arranged with a plurality of internally-threaded, blind holes. The activation or energizing of the electric motor (part of subassembly 514) operates the pump mechanism 500 to draw in oil from sump 116 and deliver oil to the downstream demands or requirements of the hydraulic system 200, as described herein.

Referring now to FIG. 10, a circuit schematic for the electric pump 120 and associated with the electric pump 120 is illustrated. The illustrated electric pump schematic of FIG. 10 includes electric pump 120 and an integral electric motor controller 526. As depicted, the electric pump assembly 524, including the pump 120 and controller 526, is mounted to sandwich housing 528. Controller 526 is electrically connected to vehicle battery 530. More specifically, some of the electrical components within controller 526 are powered by battery 530 via positive and negative battery connections 532, 534, respectively. In order to sense the ignition of the hybrid system, an ignition switch 536 is disposed on the electrical connection 538 between the positive terminal of vehicle battery 530 and controller 526. Vehicle battery 530 provides various levels of energy depending upon application, such as 12 Volts or 24 Volts, to name a couple of examples.

In order to power electric pump 120, an energy storage system 540 is electrically connected to the electric pump assembly 524. In one embodiment, electric pump 120 operates at 300 Volts DC at 2 Amps. Depending upon application, energy storage system 540 may maintain an energy level greater than 300 Volts. In those instances, the voltage level available from energy storage system 540 may be stepped down before being provided to the electric pump assembly 524 or within controller 526 before being provided to pump 120.

Because of the high voltage components located within the electric pump assembly 524, a high voltage interlock (HVIL) 542 is also provided as a safety precaution. In the illustrated embodiment, HVIL 542 is electrically and communicatively connected to electric motor controller 526. Controller 526 is therefore adapted to trigger HVIL 542 in order to electrically disconnect the electric pump assembly 524 from the rest of the vehicle if the high voltage electrical conditions become unsafe.

The electric pump assembly 524 is activated and operated by hybrid control module (HCM) 544. HCM 544 is communicatively connected to electric motor controller 526 via controller area network (CAN) bus 546. For instance, the CAN bus 546 can be a 250 k J1939-type data link, a 500 k J1939-type data link, 1000 k J1939-type data link, or a PT-CAN type data link, just to name a few examples. All of these types of data links can take any number of forms such as metallic wiring, optical fibers, radio frequency, and/or a combination thereof, just to name a few examples. As appreciated by those of ordinary skill in the art, electrical communication links, such as CAN bus 546, can be adversely affected by electromagnetic interference, or EMI. As illustrated, CAN bus 546 includes the appropriate CAN shielding in order to avoid the negative effects of EMI. Additionally, CAN terminal 548 is provided to properly ground CAN bus 546. In another embodiment, HVIL 542 is controlled by HCM 544.

SAE J1939 is the vehicle bus standard used for communication and diagnostics among vehicle components, originally by the car and heavy duty truck industry in the United States.

J1939 is used in the commercial vehicle area for communication throughout the vehicle. With a different physical layer it is used between the tractor and trailer. This is specified in ISO 11992. SAE J1939 defines five layers in the 7-layer OSI network model, and this includes the CAN 2.0b specification (using only the 29-bit/“extended” identifier) for the physical and data-link layers. The session and presentation layers are not part of the specification. All J1939 packets contain eight bytes of data and a standard header which contains an index called PGN (Parameter Group Number), which is embedded in the message's 29-bit identifier. A PGN identifies a message's function and associated data. J1939 attempts to define standard PGNs to encompass a wide range of automotive, agricultural, marine and off-road vehicle purposes.

Controller-area network (CAN or CAN-bus) is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer. CAN is a message based protocol, designed specifically for automotive applications but now also used in other areas such as industrial automation and medical equipment. CAN is one of five protocols used in the OBD-II vehicle diagnostics standard. The OBD standard is mandatory for all cars and light trucks sold in the United States since 1996, and the EOBD standard, mandatory for all petrol vehicles sold in the European Union since 2001 and all diesel vehicles since 2004.

Considering the mechanical and electrical details of the disclosed electric pump 120, the hydraulic system modes of operation, and the overall hybrid module, several novel and unobvious aspects relating to electric pump 120 are disclosed.

Referring to FIG. 11, there is illustrated another embodiment of a suitable electric pump 600 for the type or style of hybrid electric vehicle which is disclosed herein. The FIG. 11 illustration is an exploded view of the primary component parts with corresponding reference numbers as set forth below in Table II.

TABLE II Reference No. Component Part 602 End face seals 604 Dowel pin 606 Dowel pin 608 Spring washer 610 Relief valve spring 612 Valve ball 614 Valve ball 616 O-ring 618 Dowel pin 620 Pump body 622 Motor kit with bus bar 624 Dowel pin 626 Inner rotor 628 O-ring 630 Shaft 632 Cover 634 Outer rotor 636 Sealed connector 638 Screw/Bolt 640 Electrical connector 642 Screw/Bolt 654 Hex head bolt

In the illustrated embodiment of FIG. 11, four hex head bolts 654 are used (see also FIGS. 12, 17, 18 and 20). An alternative embodiment (see FIG. 12A), in terms of a hex head bolt pattern, uses three hex head bolts. The electric pump of this three-bolt pattern is identified as electric pump 600 a. The inlet conduit 644 a and outlet conduit 646 a are identified to help orient electric pump 600 a. The three bolt locations are denoted by the three flange holes 609. The decision or choice on the bolt pattern depends on other housing, casting and packaging considerations. Although the four-bolt pattern is shown in other drawings, the three-bolt pattern is considered preferable based on the current housing/casting construction and arrangement.

FIG. 12 provides a perspective view of the electric pump 600 assembly, as viewed from the opposite end of the exploded view provided by FIG. 11. FIG. 13 is a partial perspective view from still another angle or direction. FIGS. 14-16 provide partial section views of the interior of electric pump 600. Included are the inner and outer rotors 626 and 634, respectively, which comprise the gerotor 627. With continued reference to FIG. 14, the referenced “gerotor” 627 which is incorporated into electric pump 600 (including electric pump 600 a) is positioned so as to be generally concentric with the motor 629. Typically, a gerotor and motor are arranged end to end in an axial stack or sequential series. By changing the respective locations such that the gerotor 627 and motor 629 are concentric (and coaxial) there is significant space conservation producing a more compact package. The inner rotor 626 is also referred to as the inner gear 626 of the gerotor 627 (see FIG. 11). The outer rotor 634 is also referred to as the outer gear 634 of the gerotor 627 (see FIG. 11).

The motor 629 includes a stator 631, a two-piece shaft 630 and a stainless steel liner 633 concentrically positioned between the stator 631 and the permanent magnet liner 635 which separates the stainless steel liner 633 from the outer gear 634 (see FIGS. 14 and 15). The permanent magnet liner 635 includes a plurality of permanent magnets which are either bonded to and/or embedded in a stainless steel layer. This combination of integrated component parts is illustrated as a unitary structure and singularly defined as liner 635. Broken line 630 a denotes the line of separation between the two sections or portions which comprise shaft 630.

One of the design features of electric pump 600 is the longer O-ring landing as illustrated in FIG. 17. Another design feature is the separated dowel pin as illustrated in FIG. 18. Another design feature is the arrangement and orientation of connector 640 as illustrated in FIG. 19. Another design feature is a shorter inlet/outlet assembly, as illustrated in FIG. 20. Another design feature is adding clearance around each bolt head such that a standard socket wrench can be applied to the bolt head without interference. A representative example of this clearance is illustrated in FIG. 21.

With continued reference to FIG. 21, the generally cylindrical area or zone surrounding the head 654 a of bolt 654, as denoted by broken line 655, represents bolt head clearance for a standard socket wrench of an 18 mm diameter. The approximate diameter size of this clearance area or zone is 19.6 mm, a dimension which generally corresponds to the referenced socket wrench.

The assembly sequence for electric pump 600, as it is installed into the hybrid module, is illustrated in FIGS. 22-25. The first step or phase (see FIG. 22) is to align the pump body with the opening in the hybrid module which is constructed and arranged to receive the face-seal end of electric pump 600. Several points of contact or engagement must be monitored, including the O-ring 616 and the dowel pin 606.

The next phase or step in the assembly sequence, see FIG. 23, is to establish dowel pin engagement between dowel pin 606 and the machine bore in the hybrid module. At this phase in the assembly sequence, the O-ring 616 has not yet been contacted for compression and the face seals 602 are not yet in abutment against the interior surface of the hybrid module.

As the dowel pin 606 continues into the machined bore 660 of the hybrid module, contact and compression of O-ring 616 begins as the enclosing surface of the hybrid module begins to push against the outwardly protruding portion of the O-ring 616, see FIG. 24. Abutment of face seal 602 has not yet occurred at this phase of the assembly sequence. The final phase, see FIG. 25, has the dowel pin 606 fully inserted into the receiving bore 660 and the face seal 602 pushed into abutment (i.e., engagement) against the inner surface of the hybrid module.

With continued reference to FIGS. 11, 12, and 13, the assembled electric pump 600 includes an electrical connector 640 at one end and the inlet and outlet conduits 644 and 646, respectively, at the opposite end. Inserted and secured into the end of each conduit 644 and 646 is a face seal 602. Internally, the outlet conduit 646 includes a one-way valve 648 (see FIG. 16) and a pressure regulating and reducing valve (PRV) 650. The one-way valve 648 includes valve ball 614 and dowel pin 618. The PRV 650 includes valve ball 612, valve spring 610, and dowel pin 604 (see FIG. 16). The PRV 650 is used to manage the hydraulic fluid pressure within the pump and thus within the exiting flow path via outlet conduit 646. Valve 648 allows the hydraulic fluid to exit based on the flow rate and pressure created by the gerotor pumping mechanism. Essentially no resistance is offered by ball 614 which only acts to prevent reverse flow. If the hydraulic fluid pressure within pump 600 (or pump 600 a) and seen within conduit 646 is too high, ball 612 pushes up against spring 610 and a by-pass passage is opened for hydraulic fluid to leave the electric pump and return to sump. The use of PRV 650 protects the interior of pump 600 from excessive internal pressures. An elevated pressure might be due to a blockage or other restriction. Once the elevated pressure is relieved, the PRV 650 closes. The threshold pressure to open PRV 650 is managed by the size of ball 612 and by the selected spring constant for spring 610. In the exemplary embodiment PRV 650 has its threshold pressure set at 900 Kpa±70 Kpa.

Another design feature which is incorporated into the construction of electric pump 600 (as well as electric pump 600 a) pertains to the construction of one or more of the dowel pins 606 and 624. Referring to FIG. 26, a generic dowel pin 619 is illustrated as being representative of dowel pins 606 and/or dowel pins 624. Dowel pin 619 includes a swirl cut pattern which is denoted by spiral groove 619 a. This dowel pin groove 619 a is constructed and arranged to prevent “pressure lock”. When a smooth and close line-to-line fitting dowel pin is inserted into a bore, the trapped air can create an abutment to the continued advancement of the dowel pin. This air pressure lock can be eliminated by allowing the otherwise trapped air to escape via the spiral groove or vent groove 619 a.

Another design feature which is incorporated into the construction of electric pump 600 (as well as electric pump 600 a) pertains to the use of tamper-proof threaded fasteners. With reference to FIG. 27, threaded fasteners 638 and 642 include a head construction with a fluted recess 638 a and 642 a, respectively, as well as a center post. The unique shape of each recess 638 a and 642 a, along with the center post, is such that a special tool is required in order to install and remove these tamper-proof threaded fasteners. Conventional hand tools, such as flat blade screwdrivers, phillips screwdrivers and allen wrenches are not suitable as a means to remove these threaded fasteners. Since these types of hand tools would be the types typically available in the field, providing a specialized shape which requires a special tool clearly enables the intention of providing these threaded fasteners as “tamper-proof” threaded fasteners.

One of the design improvements offered by electric pump 600 is a more compact construction by shortening the extended length of the inlet and outlet conduits 644 and 646, respectively, relative to face 652 which abuts up against the inner surface of the hybrid module as hex head bolts 654 are tightened. As noted above, there are two embodiments, one embodiment has a four-bolt pattern (bolts 654) and the other embodiment has a three-bolt pattern. The referenced distance (d) (see FIG. 20) is approximately 69 mm. An earlier prototyped version of the disclosed electric pump 600 set this dimension (d) at approximately 79 mm. This more compact design results in a smaller electric pump and a smaller electric pump has less weight. Less weight results in better fuel economy.

This earlier prototyped version also incorporated an alignment dowel pin as part of one of the four hex head bolt locations. This “incorporated” construction used a hollow dowel and the corresponding hex head bolt extended through the dowel (i.e., concentric) such that dowel alignment and bolting occurred essentially at the same axial location. Another design improvement added to electric pump 600 was to separate the dowel pin 606 from the location of the corresponding hex head bolt 654 as now shown in FIGS. 12 and 18. A separate portion 656 is included as part of the pump body 620 for receiving and seating one end of dowel pin 606. This relocation contributes to a more accurate alignment procedure, a more accurate alignment in the resulting assembly, and less risk of interference as the hex head bolts are tightened.

Another improvement introduced into electric pump 600 is a longer O-ring landing as compared to an earlier prototyped version. By “longer”, what is meant is that the lateral section diameter of the O-ring body is larger in the current embodiment as compared to the earlier prototyped version. In turn, this larger diameter in lateral section means that the receiving groove has a larger diameter and thus in an axial or longitudinal direction is “longer”. Having a larger O-ring provides more elastomeric material for compression and a larger area of sealing contact. The result is a larger and more effective sealing interface at the location of the O-ring relative to the hybrid module.

Referring to FIG. 19, the connector 640 has a different orientation when used with the three-bolt pattern illustrated in FIG. 12A. This revised orientation makes assembly and the electrical connections easier.

While the preferred embodiment of the invention has been illustrated and described in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that all changes and modifications that come within the spirit of the invention are desired to be protected. 

What is claimed is:
 1. An electric pump for a hybrid vehicle comprising: a pump body defining a flow inlet conduit and a flow outlet conduit; an electric motor positioned within said pump body, said electric motor including a stator; and a gerotor positioned within said pump body, said gerotor being constructed and arranged so as to be generally concentric with and positioned radially inwardly of said stator.
 2. The electric pump of claim 1 wherein said electric motor further includes a two-piece shaft.
 3. The electric pump of claim 1 wherein said electric motor further includes a stainless steel liner.
 4. The electric pump of claim 1 wherein said electric motor further includes a permanent magnet liner.
 5. The electric pump of claim 4 wherein said permanent magnet liner includes a plurality of permanent magnets received within a stainless steel liner.
 6. The electric pump of claim 1 wherein the gerotor includes an outer rotor and an inner rotor.
 7. The electric pump of claim 1 which further includes a one-way valve positioned in said flow outlet conduit.
 8. The electric pump of claim 1 which further includes a pressure regulating valve positioned in said flow outlet conduit.
 9. The electric pump of claim 1 which further includes a dowel pin for use in alignment of said electric pump with a hybrid module.
 10. The electric pump of claim 9 wherein said dowel pin defines a pressure lock groove.
 11. The electric pump of claim 1 which further includes a cover which is attached to said pump body.
 12. The electric pump of claim 11 wherein a tamper-proof threaded fastener is used to attach said cover to said pump body.
 13. The electric pump of claim 11 which includes an electrical connector which is attached to said cover.
 14. The electric pump of claim 13 wherein a tamper-proof threaded fastener is used to attach said electrical connector to said cover.
 15. An electric pump for a hybrid vehicle comprising: a pump body; an electric motor positioned within said pump body, said electric motor including a stator, said stator defining an interior volume; and a gerotor positioned within said pump body, said gerotor being constructed and arranged so as to be generally concentric with said stator and positioned within said interior volume of said stator.
 16. The electric pump of claim 15 wherein said electric motor further includes a two-piece shaft.
 17. The electric pump of claim 15 wherein said electric motor further includes a stainless steel liner.
 18. The electric pump of claim 15 wherein said electric motor further includes a permanent magnet liner.
 19. The electric pump of claim 18 wherein said permanent magnet liner includes a plurality of permanent magnets received within a stainless steel liner.
 20. An electric pump for a hybrid vehicle comprising: a pump body including a flow inlet and a flow outlet; and an electric motor and gerotor arrangement position within said pump body, said arrangement including a generally concentric combination of a stator, a metal liner, a permanent magnet liner, an outer gear, an inner gear and a shaft.
 21. The electric pump of claim 20 wherein said metal liner is a stainless steel liner.
 22. The electric pump of claim 20 wherein said shaft is constructed and arranged as a two-piece shaft. 